Magnetic strips are used on many surfaces such as credit cards and the like to store data information related to anything from bank account information to security access codes. Such information is generally a predetermined sequence of digital zeros and ones which are read by a magnetic read head. The signals generated by the magnetic read head are deciphered and the data information encoded therein is determined.
Conventional systems and methods to determine the data held by the two frequency coherent phase signal held within magnetic strips are not without problems. Commonly, the two frequency coherent phase signal comprises a number of negative and positive transitions that oscillate above and below a predetermined centerline forming a number of consecutive positive and negative peaks. The actual data is represented by the zero crossings of the two frequency coherent phase signal where a signal zero crossing within a predetermined time period represents a logical zero, and two zero crossings within the same predetermined time period indicates a logical one. It is often the case, however, that the magnitude of the negative and positive peaks are diminished due to wear and tear on the magnetic strip, as well as exposure to extraneous magnetic fields that change the nature of the two frequency coherent phase signal. Also, sometimes a particular positive or negative transition may develop a "hook and shelf" waveform that often times causes the interpreting systems to believe there are extra zero crossings resulting in error. The waveform can also vary based on the magnetic material of the magnetic strip and the swipe speed.